With continuous increase of living standard, people pay more and more attention to house cleaning. In general, mop is the most widely used cleaning tool to clean a floor. However, aside from conventional manual cleaning tools, rapid advance of technology has spawned automatic cleaning apparatus that does not need manual operation.
For instance, R.O.C. patent No. M377197 discloses a releasing system for an automatic cleaning robot comprising a body which is an automatic cleaning robot with a self-moving control logic containing an action control unit held therein. The action control unit is an electronic element assembly to control body movements through a logic setting. The body has a movable means located at the bottom thereof that is electrically connected to the action control unit and driven to control body movements, and at least one auxiliary wheel located at the bottom of the body to incorporate with the movable means to support the body in an upright manner and keep the body moving steady. The auxiliary wheel has two side walls with at least one hole formed thereon to intermittently cover light between the side walls during rotation thereof. The body also has a detecting assembly which includes a signal sending element and a corresponding signal receiving element that are electronic elements to transmit signals through a specific light source and located at two sides of the auxiliary wheel corresponding to the hole. When the auxiliary wheel rotates, the signal sending element sends a light signal to pass through the hole of the auxiliary wheel and intermittently transmit to the signal receiving element. The signal receiving element is electrically connected to the action control unit of the body. In the event that the body encounters an obstacle and cannot move forwards, the auxiliary wheel which is not mechanically driven remains still without rotating due to the body is not moving, hence light transmission between the signal sending and receiving elements is interrupted due to stop of rotation of the auxiliary wheel. This serves as the basis to judge the body being stopped without moving. Then a backward moving command is issued to relieve the body from the dilemma.
The previous technique uses “whether the signal receiving element receives an intermittent signal” as the judgment basis, thus it requires a full stop of the auxiliary wheel to make the judgment. However, the auxiliary wheel does not stop instantly in some special conditions, for instance, when the auxiliary wheel moves to a stairway and suspends, it continuously rotates for a while before stops, or when the cleaning apparatus bumps into an obstacle, the auxiliary wheel first reverses before rotating forwards and does not stop until the impact force has been fully absorbed. In these situations, the cleaning apparatus cannot make a correct judgment instantly when it encounters an abrupt condition, and veering timing is delayed. This could cause falling or damage of the cleaning apparatus.